Is there an existing protocol or modulation method where multiple data bits are sent over a single wire at once or maybe an additional ground line (like serial communication)?
I know there are methods like PSK or FSK where phase or frequency of carrier is altered to represent different bits or states of signal, but those changes in phase or frequency are transmitted one after another i.e. serially and not at once.
Is there an existing communication or modulation method or protocol which can send multiple data bits at once and not one after another using the shifting done in PSK or FSK?
Best Answer
16-QAM transmits 4 bits simultaneously by modulating both the phase angle and the carrier amplitude: -
At the receiving end, the noise added during transmission propagation may make the bits look like this: -
But, providing there is still a gap between data received and the halfway point between symbols you can detect it.
So, if you understand the noise in your channel and your channel bandwidth is accommodating, you will be able to send more than one bit simultaneously (as suggested by the Shannon-Hartley theorum): -